The number of moles of that will be needed to completely react with exactly one mole of sulphite ion — Redox Reactions and Volumetric Analysis Chemistry Question

💡 Solution & Explanation

In an acidic medium, $KMnO_4$ reduces to $Mn^{2+}$ (n-factor = 5). The sulphite ion ($SO_3^{2-}$, where S is +4) oxidizes to sulphate ($SO_4^{2-}$, where S is +6) (n-factor = 2). Equivalents of $KMnO_4$ = Equivalents of Sulphite $\Rightarrow Moles \times 5 = 1 \times 2 \Rightarrow Moles = 2/5$.